1. The Field of the Invention
The present invention relates to a method for locating magnetic structural bodies within the earth and in particular to a method using neural networks for determining the subsurface location, geometry and depth to basement of these bodies from aeromagnetic data.
2. The Prior Art
Determination of the location and the depth to basement faults and structures in the earth is one of the most important reconnaissance exploration tools in the petroleum exploration industry. This is because many hydrocarbon reservoirs are associated with uplifted basement fault blocks and accurate mapping of subsurface structures greatly improves exploration well success rates and lowers the cost of finding hydrocarbons in sedimentary basins.
Subsurface geologic structure is commonly deduced from the mapping of surface structures and features, well log correlations, and by seismic reflection and refraction profiling. However, surface features do not always reflect deep structure when masked by surficial alluvium and moderately lithified shallow sediments. Also, the high cost of drilling deep exploratory well holes and collecting reflection seismic data often preclude their economic usefulness in delineating deep structures. Thus surveys which measure the magnetic field at or above the earth's surface, particularly from an airplane (aeromagnetics), can be an economic, environmentally attractive alternative to these other methods in unexplored or underexplored sedimentary basins.
Currently, aeromagnetic data are interpreted using combinations of simple computational and empirical techniques. The following Table I lists several of the manual and computer techniques currently used to predict location and depth of magnetic basement structural features.